1. Field of the Invention
The present invention relates to wind speed and direction measurements. More specifically, the present invention relates to a portable device and method for measuring wind speed and relative direction as applied to golf club selection and golf swing determination.
2. Description of the Related Art
There are numerous uses for the measurement and indication of wind speed and direction. Traditional meteorological measurements have long included wind speed and direction. Many outdoor activities benefit from wind speed and direction measurements as well. Aviation, boating, construction, recreation, and sports activities all benefit from having current information about wind speed and direction.
Meteorologists have long employed the rotary-cup anemometer and weather vane to measure wind speed and direction, respectively. These are both mechanical devices that are located above local terrain and structures, typically on an elevated pole, that react to air movement to produce the desired information. In addition to mechanical devices, the use of electrically self-heated resistors, hot wires, and hot films as thermal anemometer transducers are known in the prior art. In such devices, a heated resistive element serves as a sensing element. The heated element""s physical geometry is used to define its spatial response to impinging airflow. The sensing transducer has a non-zero temperature coefficient of resistance and is maintained at feedback-controlled constant resistance. Transducer element pairs are used to determine direction and in some cases they are used to determine both speed and direction.
The common drawback in the prior art teachings for measuring wind speed and direction is in their application to a portable measurement unit. The rotary anemometer and wind gauge need to be mounted in a fixed position, as they are relatively large and unwieldy for portable applications. In the thermal devices, very large amounts of electrical current are required to maintain the self-heated resistive element. This implies that a large battery and enclosure are required to enable operation of the device. Another limitation of the thermal device is that the resistive element has to be heated up before taking accurate measurement, which is time consuming for each measurement.
Thus there is a need in the art for an apparatus and method for measuring wind speed and direction that is compact, portable, and that does not consume large amounts of power in operation.
The need in the art is addressed by the apparatus and methods of the present invention. A wind gauge is taught that includes a controller and a first microphone positioned to engage wind pressure from a first relative direction. The controller is coupled to receive a first audio signal from the first microphone, and to compare the first audio signal with plural threshold values, representative of wind pressure levels, to determine a first wind pressure level incident upon the first microphone.
In a specific embodiment, the wind gauge includes a memory having the plural threshold values stored therein. The controller is coupled to recall the plural threshold values from the memory. In another embodiment, a filter is added that has an input coupled to receive the first audio signal from the first microphone and an output that couples a frequency limited portion of the first audio signal to the controller. In a particular embodiment, the filter is a low-pass filter that has a corner frequency of approximately eighty-Hertz. In a specific embodiment, the microphone is a condenser microphone. The plural threshold values may be correlated to a wind speeds, and may be organized as a wind speed map.
In a specific implementation of the present invention, the controller is a digital signal processor. Also, an analog to digital converter is coupled to digitize the first audio signal and output a digital representation of the first audio signal to the digital signal processor. A display is coupled to the controller, or digital signal processor, to display an indicia of the first wind pressure level, which may be the wind speed.
To operate within a wide range of signal levels, a gain stage may be coupled between the microphone and the controller and operated to control the gain of the first audio signal. Thus, the controller determines the signal level of the first audio signal and further controls the gain stage to adjust the gain of the first audio signal into a reasonable operating range.
In a specific implementation that advantageously determines wind direction, as well as magnitude, a second microphone is positioned to engage wind pressure from a second relative direction. The controller is coupled to receive a second audio signal from the second microphone, and to compare the second audio signal with the plural threshold values to determine a second wind pressure level incident upon the second microphone. A housing supports the microphones and the controller, and has a direction indicator thereon which establishes the reference for the relative directions. In addition, a third microphone may be positioned to engage wind pressure from a third relative direction and a fourth microphone may be positioned to engage wind pressure from a fourth relative direction. The controller is then coupled to receive a third and fourth audio signal from the third and fourth microphones. In addition, the controller operates to compare the third and fourth audio signals with the plural threshold values to determine third and fourth wind pressure levels incident upon the third and fourth microphones. In a particular application, the first, second, third, and fourth relative direction are positioned equidistant about a circle, thereby defining four quadrants of directions therebetween. The controller operates to compare the first, second, third, and fourth wind pressure levels and determines which of the four quadrants the wind pressure is impinging upon.
In another specific application of the present invention, the controller processes the first audio signal and the second audio signal to produce a first signal magnitude and a second signal magnitude, respectively. The controller may repetitively sample the audio signals over a predetermined window of time to establish the first signal magnitude and the second signal magnitude. In a refinement, the controller sums the first signal magnitude and the second signal magnitude to determine if a minimum total signal magnitude exists, thereby indicating a minimum measurable wind pressure. Further, the controller may compare the first signal magnitude and the second signal magnitude to determine if a minimum threshold signal magnitude difference exists, thereby indicating the presence of wind. The controller may define a first wind vector as a combination of the first signal magnitude and the first relative direction, and may define a second wind vector as a combination of the second signal magnitude and the second relative direction. Then, the controller can operate to calculate a resultant wind vector based on the first wind vector and the second wind vector.
In a specific embodiment, the wind gauge further includes a housing supporting the microphones and the controller. The housing has a direction indicator thereon which establishes the reference for the relative directions. The controller utilizes the resultant wind vector to calculate a head wind pressure and output a golf club selection adjustment factor. In addition, the controller may utilize the resultant wind vector to calculate a crosswind pressure and output a golf swing direction adjustment factor. In another specific embodiment, the wind gauge further includes a temperature sensor coupled to the controller for sensing ambient temperature, and the controller operates to read the ambient temperature and calculate a wind chill factor based on the ambient temperature and the first wind pressure level.
In an illustrative embodiment of the present invention, the teachings are applied to a golf wind gauge. The golf wind gauge utilizes plural microphones. A housing supports the plural microphones at positions spaced along a compass to engage wind pressure from plural relative directions that define plural segments of the compass therebetween. The housing has a reference direction indicator. Plural low-pass filters are coupled to receive plural audio signals from the plural microphones and output plural frequency limited portions of the plural audio signals. And, plural gain stages are coupled to receive and control the gain of the plural signals. A memory has plural threshold values, correlated to wind speeds, stored therein. Also, plural analog to digital converters are coupled to digitize the plural signals and output digital representations thereof A controller is coupled to receive the digital representations of the plural signals and determine the signal levels thereof by repetitively sampling the plural signals over predetermined windows of time. The controller operates to control the plural gain stages to adjust the gain of the plural signals. The controller is coupled to recall the plural threshold values from the memory and compare the plural signals therewith to determine plural wind pressure levels incident upon the plural microphones. In operation, the controller sums the plural signals to determine if a minimum total signal magnitude exists, thereby indicating a minimum measurable wind pressure. Also, the controller compares the plural signal levels in pair combinations to determine if a minimum threshold signal magnitude difference exists, thereby indicating the presence of wind, and within which of the plural compass segments the wind is impinging upon.
Having determined the segment the wind is heading into, the controller defines two wind vectors as combinations of the two wind pressure levels and the two relative directions adjacent to the one of the plural compass segments into which the wind impinges. Then, the controller calculates a resultant wind vector based on the two wind vectors. A display is coupled to the controller and has an indicia of wind direction, an indicia of golf club strength adjustment, and an indicia of golf swing direction adjustment. The controller activates the indicia of wind direction in accordance with the direction of the resultant vector. It also activates the indicia of golf club strength adjustment in accordance with a component of the resultant vector that is aligned with the reference direction. And, activates the indicia of golf swing direction adjustment in accordance with a component of the resultant vector that is orthogonal to the reference direction.